221211664 has 20 divisors (see below), whose sum is σ = 429286140. Its totient is φ = 110428160.

The previous prime is 221211643. The next prime is 221211673. The reversal of 221211664 is 466112122.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 93702400 + 127509264 = 9680^2 + 11292^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 529 + ... + 21040.

It is an arithmetic number, because the mean of its divisors is an integer number (21464307).

Almost surely, 2^221211664 is an apocalyptic number.

It is an amenable number.

221211664 is a deficient number, since it is larger than the sum of its proper divisors (208074476).

221211664 is a wasteful number, since it uses less digits than its factorization.

221211664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22218 (or 22212 counting only the distinct ones).

The product of its digits is 1152, while the sum is 25.

The square root of 221211664 is about 14873.1860742747. The cubic root of 221211664 is about 604.7873159019.

Adding to 221211664 its reverse (466112122), we get a palindrome (687323786).

The spelling of 221211664 in words is "two hundred twenty-one million, two hundred eleven thousand, six hundred sixty-four".